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Stingy aliens may call us on cheap rates only
In alien civilisations, do accountants have the upper hand? If so, our strategy for searching for extraterrestrials could be misguided.
A new study suggests that cost-effective galactic radio transmissions would be at higher frequencies than SETI projects traditionally monitor, and ET's attempts to make contact would be only few and far between.
"If ET was building cost-effective beacons, would our searches have detected them? The answer turns out to be no," says James Benford, president of the company Microwave Sciences in Lafayette, California.
Cosmic water hole
Aliens wishing to communicate would probably broadcast at frequencies between 1 and 10 gigahertz, where there is less astronomical background noise than in other wavebands. Most SETI projects tune in to the "cosmic water hole" waveband between 1.42 and 1.72 gigahertz. The reasoning goes that alien astronomers might expect earthly scientists to be looking there anyway as this is the frequency of radiation emitted by interstellar hydrogen and hydroxyl clouds.
But this fails to consider the cost to aliens. "Societies are always constrained by their resources," Benford points out. "Why did cathedrals take centuries to build? Partly because they had only so many artisans, but also their capital was limited."
Benford's analysis of the economics of extraterrestrial beacons with his brother Gregory at the University of California, Irvine, and son Dominic at NASA's Goddard Space Flight Center in Maryland suggests that aliens would choose to transmit at nearer to 10 gigahertz, as this makes it easier and cheaper to create a powerful beam.
Little and often
Continue www.newscientist.com/article/dn19206-stingy-aliens-may-call-us-on-cheap-rates-only.html
